Medical devices may be external or implantable, and may be used to deliver electrical stimulation therapy to various tissue sites of a patient to treat a variety of symptoms or conditions. A medical device may deliver electrical stimulation therapy via one or more implantable leads that place electrodes proximate to target locations in a patient. Examples of target locations include anatomical structures in the brain for deep brain stimulation (DBS), the spinal cord for spinal cord stimulation (SCS), pelvic nerves for pelvic stimulation, nerves in the gastrointestinal tract for gastric stimulation, and various peripheral nerves for peripheral nerve field stimulation (PNFS).
A clinician may select values for a number of programmable parameters in order to define the electrical stimulation therapy to be delivered to a patient. For example, the clinician may select two or more active electrodes for delivery of the stimulation, polarities of the electrodes, voltage or current pulse amplitude, stimulation pulse width, and stimulation pulse frequency as stimulation parameters. The clinician may select these parameters to locate, direct and shape stimulation fields, e.g., to provide stimulation that promotes therapeutic efficacy while avoiding or suppressing undesirable side effects.